The present invention relates in general to electrical impedance tomography, and in particular to a new and useful apparatus for non-invasive clinical diagnosis.
The present invention represents the culmination of a development which can be traced back to the disclosure of U.S. Pat. No. 4,920,490 entitled PROCESS AND APPARATUS FOR DISTINGUISHING CONDUCTIVITIES BY ELECTRIC CURRENT COMPUTED TOMOGRAPHY. One conductivity in a body can be distinguished from another using the teaching of this patent which is incorporated here by reference.
The following co-pending applications which are also incorporated here by reference, track the further development of the invention. Ser. No. 07/591,615 filed Oct. 2, 1990 and entitled CURRENT PATTERNS FOR IMPEDANCE TOMOGRAPHY, discloses now U.S. Pat. No. 5,272,624 a method for creating simplified current patterns for use in impedance imaging.
Ser. No. 07/727,075 filed Jul. 9, 1991 now U.S. Pat. No. 5,390,110 and entitled A LAYER STRIPPING PROCESS FOR IMPEDANCE IMAGING, discloses a method of creating an impedance image, layer by layer into the thickness of a body.
Ser. No. 07/734,591 filed Jul. 23, 1991 now U.S. Pat. No. 5,381,333 and entitled CURRENT PATTERNS FOR ELECTRICAL IMPEDANCE TOMOGRAPHY, discloses an adaptive process for calculating the best current patterns to be applied to the electrodes of a device for creating an impedance image.
Ser. No. 07/808,795 filed Dec. 16, 1991 now U.S. Pat. No. 5,284,142 and entitled THREE-DIMENSIONAL IMPEDANCE IMAGING PROCESSES, discloses a method for mathematically manipulating the voltages or currents measured from an array of electrodes around the body, to form an impedance image of the three dimensional space within the body.
The foregoing patent and pending applications are all incorporated by reference in that they may help better explain the present invention and its usefulness in electrical impedance tomography (EIT) and electric current computed tomography (ECCT).
Although the above-identified patent applications do not represent prior art to the present application, the prior art does contain alternate examples of apparatus and equipment that is useful in the field of tomography.
U.S. Pat. No., 4,539,640 to Fry, et al. discloses an apparatus and method for impedance imaging of a patient's body utilizing an array of electrodes in electrical contact with the outer surface of the patient's torso. Circuitry disclosed in this patent is capable of multiplexed application of current patterns.
U.S. Pat. No. 4,263,920 to Tasto, et al. also discloses an imaging apparatus which utilizes an array of multiple electrodes for use in measuring resistant paths through a body.
It is also known to use electrical bridges to measure impedance between two distinct points on a body. U.S. Pat. No. 4,911,175 to Shizgal is one example.
U.S. Pat. No. 4, 947,862 to Kelly also discloses an apparatus utilizing electrical contacts on the body for measuring a composition of the body.